Proton Auroras Equatorward of the Oval as a Manifestation of the Ion-Cyclotron Instability in the Earth’s Magnetosphere (Brief Review)

Abstract

Different types of proton auroras observed by the IMAGE satellite equatorward of the proton aurora oval are briefly reviewed. These auroras are caused by the precipitation of energetic protons from the Earth’s magnetosphere during the development of the ion-cyclotron instability. In addition to the previously considered types of proton auroras (spots, evening arcs, and dayside flashes), a new type is described: longlasting proton auroras on the dayside. The scheme of interrelation between different proton auroras equatorward of the oval with the distribution of cold plasmaspheric plasma is given.